1. Field of the Invention
The present invention relates to an antenna device included in an RFID system or the like and a communication apparatus including the antenna device.
2. Description of the Related Art
In recent years, communication terminals, such as cellular phones, which incorporate HF-band RFID systems and which themselves can be used as reader/writer devices or RFID tags have come into widespread use. However, with the reduction in size and increase in functionality of communication terminals, there may be a case in which it is difficult to provide a sufficient space for an antenna in the housing of a communication terminal.
Accordingly, Japanese Unexamined Patent Application Publication No. 2005-318329, for example, describes a known jacket-shaped device that can be detachably attached to a communication terminal. The jacket-shaped device includes an antenna coil, and an end portion of the antenna coil extends to a surface terminal. When the jacket-shaped device is attached to the communication terminal, the surface terminal is connected to a feeding circuit provided on the communication terminal through a connector or a spring contact.
The jacket-shaped device described in Japanese Unexamined Patent Application Publication No. 2005-318329 is formed of a thin plate-shaped resin member so that it can be attached to the communication terminal as inconspicuously as possible. Therefore, when the jacket receives an impact or is strongly grabbed, there is a risk that the jacket itself will be bent and a connecting portion between an antenna coil and a wiring conductor will break. In addition, in the case where the antenna coil and the wiring conductor are integrated inside the jacket, there is also a risk that the connecting portion between the antenna coil and the wiring conductor will break during a resin injection molding process. Thus, it is difficult to reliably integrate the antenna and the wiring conductor inside a thin plate-shaped resin member.